What does Matthew 15:4 mean?
Jesus sounds justifiably angry in these verses. He is talking to a group of Pharisees who have come a long way to challenge His authority as a rabbi. Their current complaint is that He doesn't require His disciples to follow a specific tradition about handwashing. That tradition, though, is not one of the commands of God in Scripture. The implication is that if Jesus isn't cooperating with their man-made rules, then He is not a good teacher.Jesus has ignored their challenge, which is really a rhetorical trap. Rather than "defend" something which need not be explained, Jesus has chosen to use the attack to point out the Pharisees' deep hypocrisy. While they criticize Jesus for not following a man-made rule, they themselves use man-made rules to avoid following the actual commands of God!
The fifth of the Ten Commandments is what Jesus has in mind: Honor your father and mother (Exodus 20:12). Jesus adds a negative version of the command from Exodus 21:17: Whoever reviles—meaning to curse or speak evil of—their father or mother is deserving of death. Clearly, this commandment demands that children care for and respect their parents. And yet, as Jesus will show, the man-made laws which the Pharisees defend enable people to effectively break that commandment.